Normal Swallow Physiology

Question 1

What are the CNs involved in mastication?

Answer 1

V Trigeminal (sensory - tongue) 
VI Facial (hold cheeks closed)
XII Hypoglossal (motor - tongue)

Question 2

What is necessary for mastication?

Answer 2

Adequate dentition, alertness, awareness of bolus during feeding and in mouth, sensory feedback

Question 3

During bolus holding which two structures contract and why?

Answer 3

tongue and and velum, to prevent posterior spillage

Question 4

When does the pharyngeal swallow start?

Answer 4

When the hyoid moves superiorly and anteriorly… has nothing to do with position of the bolus

Question 5

Which cranial nerves are associated with the initiation of the pharyngeal swallow?

Answer 5

CN IX and X – sensory receptors in oropharynx and posterior tongue

Question 6

The signal for the pharyngeal swallow to start is sent from the CNs to which part of the brain?

Answer 6

brainstem

Question 7

What are some of the places where the bolus may cause the initiation of the pharyngeal swallow?

Answer 7

anterior faucial arches, tongue base, epiglottis, larynx

Question 8

What are the stage events of the pharyngeal swallow?

Answer 8

laryngeal closure, tongue base retracts, superior and anterior hyolaryngeal movement, velopharyngeal closure, pharynx contraction, opening of PES

Question 9

How does the larynx close and why is this important?

Answer 9

from bottom to top. maximum protection of airway… three levels of protection

Question 10

why does the tongue base retract during swallowing?

Answer 10

makes contact with posterior pharyngeal wall – increases pressure on the bolus and helps push it down. also aids in epiglottic inversion

Question 11

How is the suprahyoid pulled superiorly and anteriorly?

Answer 11

contraction of the suprahyoids

Question 12

Which CNs are involved with contraction of suprahyoids?

Answer 12

CN V, VII, XII

Question 13

Hyolaryngeal excursion also leads to:

Answer 13

epiglottic inversion, anterior tilting of the arytenoids, pulling open of the PES

Question 14

When the velum is weak and doesn’t close, what can happen?

Answer 14

food makes its ways into nasal cavity, patient has difficulty building up pressure to push the bolus down

Question 15

Which CNs are responsible for pharyngeal constriction?

Answer 15

CN IX, X, XI

Question 16

What are the three factors that lead to opening of the PES?

Answer 16

anterior movement of the larynx, bolus driving pressures (force the PES open), muscle relaxation (brainstem releases PES from its contraction)

Question 17

What is the name of the part of the brainstem that generates the swallowing motor pattern?

Answer 17

Nucleus ambiguus

Question 18

What does the Nucleus Tractus Solitarius do?

Answer 18

processes sensory information and sends it to nucleus ambiguus. important for pharyngeal swallow initiation.

Question 19

What are the cortical areas of the brain that are involved in swallowing?

Answer 19

premotor cortex, supplementary motor cortex, primary motor cortex, primary somatosensory cortex

Question 20

What are the subcortical areas involved in swallowing?

Answer 20

BG, thalamus, insula, cerebellum, cingulate gyrus, white matter tracts

Question 21

Which part of the brainstem is primarily involved in swallowing?

Answer 21

medulla